Simplex lattice design for optimization of the mass ratio of Curcuma longa L., Curcuma zedoaria (Christm.) Roscoe and Curcuma aromatica Salisb. to maximize curcuminoids content and antioxidant activity.

The aim of this work was to optimize the mass ratio of three Curcuma plants' rhizomes to obtain the highest curcuminoid content and antioxidant activity using the simplex lattice design. The selected Curcuma plants were C. longa, C. zedoaria and C. aromatica. The simplex lattice design was applied in the work. The individual curcuminoids (curcumin, demethoxycurcumin and bis-demethoxycurcumin) and total curcuminoid content were determined using high-performance liquid chromatography. Curcuma longa alone provided the highest content of bis-demethoxycurcumin and demethoxycurcumin. A mixture of C. longa and C. aromatica in the mass ratio of 72:28 % provided the highest curcumin content. The results showed that C. longa alone exhibited the highest antioxidant activity.